Method of forming hollow plastic articles



May 1962 D. G. REMPEL ET AL 3,031,720

METHOD OF FORMING HOLLOW PLASTIC ARTICLES Original Fild Feb. 27, 1957 4Sheets-Sheet l INVENTORS DIETRICH G. REMPEL FRANK A. PFEIFENROTHATTORNEYS y 1962 D. e. REMPEL ETAL 3,031,720

METHOD OF FORMING HOLLOW PLASTIC ARTICLES 4 Sheets-Sheet 2 OriginalFiled Feb. 27, 1957 INVENTORS DIETRICH G. REMPEL QRBANK A PFEIFENROTH pWM @4,

ATTO R N EYS May 1, 1962 D. G. REMPEL ETAL 3,031,720

METHOD OF FORMING HOLLOW PLASTIC ARTICLES Original Filed Feb. 27, 1957 4Sheets-Sheet 5 INVENTORS DIETRICH G. REMPEL FgeNK A. PFEIFENROTHATTORNEYS y 1962 D. G. REMPEL ETAL 3,031,720

METHOD OF FORMING HOLLOW PLASTIC ARTICLES 4 Sheets-Sheet 4 OriginalFiled Feb. 27, 1957 INVENTORS DlETRlGH. G. REMPEL BYFRANK A. PFEIFENROTH ATTORNEYS United States Patent Ofiice 3,631,720 Patented May 1,1962 3,031,720 METHUD OF FOPMHNG HOLLOW PLASTEC ARTKQLES Dietrich G.Rernpel and Frank A. Pfeifenroth, Akron, Ohio, assignors to RempelManufacturing, 1110., Akron, Ohio, a corporation of (lhio Originalapplication Feb. 27, 1957, Ser. No. 642,822, now Patent No. 2,978,244,dated Apr. 4, 1961. Divided and this application Feb. 10, 1960, Ser. No.7,917

4 Claims. (Cl. lit-47.5)

This invention relates to improvements in methods of forming enclosedhollow articles such as toys made of plastic materials having supportingmembers located therein and extending outwardly therefrom when thehollow toy is made.

This application is a division of application Serial Number 642,822filed February 27, 1957, now Patent Number 2,978,244.

More particularly, the invention relates to hollow rubher toys, such asa pony made from rubber latex by a compound rotation process inwater-absorbing molds having a saddle member located in the mold andaway from the mold walls during the rotary casting process and with oneor more saddle supporting members extending through the mold whereby,when the pony or other toy is formed by the rotary casting process andsubsequent curing of the rubber, the pony will have the supportingsaddle inside the pony with its supporting member or members extendingoutside the pony for supporting the same.

When a toy or" plastic material, such as a hollow rubber toy, or a toyof other plastic material, is made of relatively large size, such as apony of a size which can be mounted by a child sitting on the pony, thehollow rubber or other plastic toy itself is not of sufiicient strengthto support a child. The rubber or other plastic pony may thus have abody size of around 32" and an overall size of around 44 and may have awall thickness of the rotary cast pony of only around /s of an inch.

The present invention provides an improved method for making such a toyand providing it with an internal support such as a saddle or seat andwith one or more supporting elements for supporting the saddle or seatso that when a child is seated on the pony there will be adequatesupport for the child.

The invention also includes an improved process for making a toy inwhich not only a saddle but also a neck bar or neck piece is containedinside the mold and away from the mold walls during the rotary moldingor casting operation, with a support or supports therefor extendingoutside the mold so that when the pony is molded and the moldingcomposition cured, the saddle will support the pony at the saddleportion and the neck piece can have a handle bars secured theretooutside the neck of the pony so that a child sitting on the saddle andtaking hold of the handle bars will have a rigid frame connectionbetween the saddle and handle bars.

The improved toys of the present invention with internal supportingmembers can advantageously be made by a rotary casting process in whichvulcanizable rubber latex in sullicient amount to form the toy is placedin a porous mold such as a mold made of plaster of Paris, and the toyformed by compound rotation of the mold about different axes locatede.g. at right angles to each other according to the rotary castingprocess described, for example, in the Rempel US. Patents Nos.2,469,892, 2,603,836 and 2,629,139.

In making the large toys such as the pony, the supporting member islocated in the mold away from the sides of the mold and is supported andheld by one or more supporting members extending through the mold duringthe rotary casting process, with the result that the toy is formed inthe mold without any contact of the saddle or other support with themolded toy. The mold is formed at the saddle portion of a shapeconforming to the shape of the saddle support located in the mold sothat when the toy is formed and the plastic composition cured, thesaddle support can be located at the saddle portion of the toy tosupport the same.

Special molds are required for making the toy with the supportingstructure located therein and held away from the walls of the moldduring the rotary molding operation. One mold section is provided withone or more tubular members extending inside the mold and also outsidethrough which the saddle supporting memher or members extend and withmeans for holding the saddle member away from the mold walls during therotary process.

in some cases the mold can be made of two mold members, but with a toysuch as a pony it is advantageously made of two side members and anintermediate member located between the legs of the pony and having thetubular member or members extending through the intermediate or bottommold portion so that, at the end of the rotary casting operation andafter further drying, the side members of the mold can be removed andthe intermediate or bottom portion can be used to support the molded toyduring a further drying or partial curing treatment until the toy hasbeen dried or cured sufliciently to permit it to be removed from theintermediate supporting section of the mold. Thereafter the toy can besupported on a suitable supporting frame for the further drying andcuring, after which the saddle support can be raised to thecorresponding saddle portion of the toy and the neck piece when usedraised to its final position in the neck so that laterally extendinghandles can be secured to the neck member.

In general, the toys which are made by the present process are toys ofrelatively large size and of the type where a portion, such as a saddle,is to be provided so that a child can ride the toy. In general, the toysare toys representing animals or large birds which a child can ride,including not only ponies but other animals, such as giraifes, zebras,donkeys, elephants, lions, tigers,

etc., as well as large birds, such as an ostrich, or other supportextending outside the mold so that, when the toy' is molded, the saddleor other supporting portion can be raised into contact with the saddleportion of the toy so that the toy will be supported thereby, and inturn the saddle and toy will be supported by the supporting member ormembers which extend outwardly through the bottom portion of the toy.

The supporting member or members for the saddle or other toy support areadvantageously one or more downwardly extending members such as a rod ortube which is adapted to be attached to or supported by differentsupporting structures when the toy is finished. And when a neck piece aswell as a saddle are located inside the toy with hand bars secured tothe neck piece, a child sitting on the saddle with his hands on the handbars will have a rigid supporting frame between the hand bars and thesaddle.

A toy such as a pony produced in accordance with the present inventionis advantageously supported by a spring The pony or other toy with itsdepending supporting rods or tubes can be used for many purposes andwith many different kinds of supports. The pony or other toy can thus besupported on a merry-go-round or on a bicycle or on a rocking support,etc. A rubber toy, such as a pony supported in the manner described,with a supporting saddle and neck piece, will be otherwise unsupported.And a rubber pony, or other plastic toy, having a wall thickness ofaround As" will be flexible and yieldable at other portions while therider sitting in the saddle and with hands on the handles secured to theneck piece will have these parts rigidly connected together.

A rubber toy, such as a pony, can advantageously have a bridle on thehead of the pony with reins which the rider can use, and the neck of thepony is sufficiently flexible so that by pulling on the reins the neckwill bend and will return to its original position when the pulling isdiscontinued.

The invention will be further described in connection with theaccompanying drawings illustrating one embodiment of the invention andthe forming of a hollow life-like pony of rubber by the use ofvulcanizable latex in porous molds, such as plaster of Paris molds, bythe use of the rotary casting process such as described in the patentsabove referred to.

In the accompanying drawings:

FIG. 1 shows one of two opposing side molds used in molding the pony bythe rotary molding process, this view being in perspective;

FIG. 2 shows the intermediate lower member of the mold which is locatedbetween the two side mold members, and with parts broken away, this viewbeing also in perspective;

FIG. 3 is an enlarged view of a portion of the mold section of FIG. 2,with the saddle supporting member also shown;

,FIG. 4 shows the mold section of FIG. 2 in perspective and with thesaddle and neck bar supported therein;

FIG. 5 shows the side member of FIG. 1 and the intermediate mold memberof FIG. 4 with the location of the saddle and neck member during therotary casting process;

FIG. 6 shows the molded pony with the side mold members removed, andsupported by the lower intermediate mold member;

FIG. 7 illustrates the supporting of the pony and intermediate moldmember during the further drying operation, the showing being inperspective;

FIG. 8 shows how the pony is supported during the curing or vulcanizingtreatment; and

FIG. 9 shows the completed pony, with parts broken away to show thelocation of the supporting saddle and neck bar.

The molds used .in molding the pony by the rotary casting processinclude two side members, one of which is shown in FIG. 1, and anintermediate lower mold member, shown in FIGS. 24. The wall sections ofthe molds are of water-absorbent material, such as plaster of Paris. Theside mold member 1 shown in FIG. 1 has edges 2 which, between the pointsindicated at 3 and '4, come in contact with corresponding members of theopposite side mold member. The lower portions of the edges of the sidemember, indicated at 5 and located between the points 3 and 4, matchwith the edges of the lower mold member illustrated in FIG. 2.

When the side member of FIG. 1, the lower intermediate member of FIG. 2,and the opposite side member corresponding to that of FIG. 1, are unitedtogether, they form the complete mold in which the pony is molded by therotary casting process.

In FIG. 1 projecting portions are indicated at 6 which form a recess andopening through which the handle bars are inserted, as hereinafterdescribed. The side mold members have recesses indicated at 7, forforming complementary recesses in the molded pony for receiving the backof the supporting saddle as hereinafter described.

The lower intermediate mold section 8 illustrated in FIGS. 2 to 4 hasedges 9 which match with thetwo side mold members, one of which isillustrated in FIG. 1. In FIG 2 a portion of the mold member is brokenaway to show the tubular member 11, which is molded therein when thelower mold member is formed. The mold member is formed e.g. of plasterof Paris, as indicated at It) in FIGS. 2 and 3. This tubular member 11serves for receiving and supporting the tube 12 which extendstherethrough and to which the saddle 14 is secured and which has anextension forming a neckbar terminating in the flattened portion 13having an opening therein to which the handle bars are secured, ashereafter described.

FIG. 5 shows the lower intermediate mold member and one side member withthe location of the saddle and neck bar in the mold, and with a clamp 16of U-shape having a clamping bolt 17 for holding the members 11 and 12from relative rotation during the rotary casting process. Thearrangement of the tubular member 11 in the lower mold section, and ofthe saddle supporting bar 12 shown in FIGS. 4 and 5, is such that theupper end of the member 11 supports the member 12 at a proper distanceaway from both the upper and lower portions or" the mold. And the clamp16 prevents the member 12 from rotation during the rotary castingprocess.

When the side mold section illustrated in FIG. 5 is placed in ahorizontal position and the intermediate mold member is placed thereonas illustrated in FIG. 5, the latex in proper amount for forming thepony is charged into the mold, the opposite side member is then addedand the mold members are clamped together and are ready forthe rotarycasting process.

The rotary casting process is carried out by supporting the molds inapparatus which causes rotation of the molds on axes at right angles toeach other, as described in the patent above referred to. This compoundrotation of the molds is continued until the water in the latex has beenabsorbed by the porous mold to an extent sufficient to form the moldedarticle on the walls of the mold. The compound rotation insures that allparts of the mold have the latex distributed thereover and the gradualabsorption of the water in the porous mold results in the forming of amolded pony with uniform or approximately uniform wall thickness. Theamount of latex used is such that the wall thickness of the molded andcured pony is e.g. about one-eighth of an inch, although this wallthickness can be varied somewhat.

The supporting of the saddle and neck bar in the mold away from thesides of the mold as illustrated in FIG. 5 enables the pony to be moldedin its final form without contact with the saddle and neck bar.

After the pony has been molded in the rotary casting process, the moldis removed, the top side member is lifted ofif, and the intermediatemold member and molded pony are removed from the bottom side mold memberso that the intermediate member supports the molded I pony, asillustrated in FIG. 6, which has parts broken away at 19 to show thethickness of the rubber layer at 20.

In a molded article of the size of a pony, the molded walls at thisstage do not have sufiicient strength to support the pony withoutfurther drying. To accomplish this further drying, the pony is keptsupported by the intermediate mold member, as illustrated in FIG. 6, andis subjected to a further drying of the molded pony by supporting it insuitable supports, as illustrated in FIG. 7, during this further drying.

FIG. 7 shows the pony supported by the lower mold section, with the rodsupport 21 for supporting the neck and head of the pony, and with rods22 and 23 for supporting the mold member. The clamp shown in FIGS. 5 and6 is removed and the lower end of the supporting member 12 is supportedby a bar 24.

After further drying, the pony is then removed from the lower moldmember and supported on an aluminum supporting frame, as illustrated inFIG. 8, where three supporting members are shown, two on one side, 25and 26, and one on the opposite side, 27. These aluminum supports aresecured at their upper ends to the bar 28 and at their lower ends tosupporting bars, one of which is shown for the members 25 and 26 at 2 9.A similar bar (not shown) is located on the back side to support thelower end of the member 27. Thesealuminum supports have openings 39 topermit the supporting tubes 12 to pass therethrough, and supports 31 and32 are provided for supporting the lower ends of these tubes.

The aluminum supports for supporting the pony shown in FIG. 8 have acontour which gives adequate support to the pony when it is subjected tothe final drying and curing treatment. The further drying of the moldedpony which takes place while supported on the bottom mold member, asillustrated in FIG. 7, may be, for example, one-half hour at 150 F. Thefurther drying of the molded pony when supported by the aluminumsupports as illustrated in FIG. 8 may be e.g. for a further period ofone-half hour at 150, to complete the drying. After the drying iscompleted the pony is placed in the curing oven, e.g., for a period of45 minutes at 250 F., to cure the rubber latex and form the vulcanizedrubber which forms the walls of the final pony.

When the rotary casting process is completed and the side wall membersare removed, they can be used again in further carrying out of themolding process, and the intermediate lower members can also be usedagain when they have served their purpose in supporting the pony duringthe further drying operation.

It will be understood that while the carrying out of the process in asingle mold has been described, in practice a series of molds will beoperated and a number of molds may be rotated simultaneously by thecompound rotation process on a schedule such that a series of moldedobjects can be continuously produced. The further drying and curingoperations can also be carried out in a continuous manner and with anumber of ponies molded in the manner above described.

The final molded pony is illustrated in FIG. 9, with portions at the topof the pony broken away at 33 to show the wall thickness 34 and to showthe location of the supporting saddle and neck bar in their finalposition. It will be seen that the recess 7a molded in the pony to formthe back of the saddle portion has the back of the saddle 15 locatedtherein and that the contour of the saddle portion of the pony conformsto the shape of the saddle 14. The neck bar 12 extends up into andsupports the neck and has handle bars 35 secured to the upper end of theneck bar 12 by means of the opening 13 shown in FIG. 4.

Where the supporting member 12 passes through the lower portion or bellyof the pony, the lower wall of the pony is held in proper position withreference to the supporting member, as illustrated, for example, in FIG.9, Where a clamping member or grommet 38, e.g. of rub-ber, is placed onthe supporting bar 12 and also serves to clamp the edges of the wall ofthe pony around its opening.

It will be noted from FIG. 9 that the supporting bar 12 extends downbelow the pony and is adapted to be secured to supporting frames ormembers of various kinds and that it constitutes the entire support forthe pony.

It will also be seen that the supporting bar is rigidly secured to thesaddle and to the handle bars so that when a child is seated in thesaddle of the pony and grasps the handle bars, these members are rigidlysupported with relation to each other.

The pony with a wall thickness of around A has sufficient stiffness tomaintain its normal form and yet it is resilient and yieldable whenpressure is applied except where it is supported by the saddle and bythe neck piece. Thus, the flexible nature of the neck and head of thepony is such that when a bridle is applied, as shown in FIG. 9, and achild pulls on the reins of the bridle, the head will bend so long asthe pull is applied but will return to its normal position when thereins are released. A child sitting on the saddle is rigidly supportedbut the sides of the pony are yieldable.

While the drawings illustrate the process in connection with theproduction of a pony, the process is also applicable to the productionof other hollow toys and particularly of toys which have a supportingsaddle therein, or a supporting saddle and neck piece, and where thewalls of the toy are of relatively thin plastic material and flexibleand yieldable except where supported by the rigid supports The moldingof the toy with the supporting framework located therein and held awayfrom the molds during the rotary casting process enables the supports tobe properly located in the molded toy with only a single supportingmember extending downwardly for supporting the toy. Toys can thus bemade of rubber or of other plastic materials without any seams oropenings which require subsequent closure except for the openingsthrough which the supporting member is inserted, and openings such asthat for the handle bar in the neck portion of the toy.

The final pony with its single supporting member is adapted for use formany purposes and in many different kinds of supports, such as thoseabove referred to.

While the pony illustrated has only a single downwardly extending rod ortube for supporting the saddle and neck piece during the rotary castingprocess, two or more downwardly extending members can be used, e.g., aninverted U-shaped tube, to which the saddle and neck piece are secured.

We claim:

1. The method of molding enclosed hollow plastic articles of resilientplastic material in which the plastic article is formed in a mold fromliquid plastic material with compound rotation of the mold arounddilferent axes, which comprises locating in the mold, a substantialdistance away from the walls thereof, a supporting element havingsupporting means extending out through the wall of the mold, molding thearticle in the mold without contact of the supporting element with thearticle formed by the compound rotation process, forming in the article,during the molding operation, a portion having a shape substantiallycomplementary to the supporting element, and bringing the supportingelement into contact with said complementary portion of the articleafter the molding of the article is finished.

2. The improvement in the formation of enclosed hollow rubber articlesfrom rubber latex in water absorbent molds, in which the molds arerotated around different axes during the formation of the article in themold, which comprises arranging a supporting member in the mold andholding it a substantial distance from contact with the walls of themold, molding the article in said mold while said supporting member isso held, the wall of the molded article between the supporting memberand the wall of the mold opposite the supporting surface of thesupporting member having a thickness less than the distance between saidsupporting member and said wall of the mold, said supporting memberhaving a portion extending outwardly through the mold when the articleis formed and forming a support for the toy after the article is formed,and bringing the supporting member into supporting engagement with saidcomplementary portion of the article after the article is formed.

3. The improvement in the making of enclosed hollow plastic toys ofresilient plastic material in :a multi-part mold with compound rotationof the mold about two axes during the forming of the hollow toy therein,which comprises providing in the mold, during the molding operation, aportion corresponding to a saddle portion of the toy, locating a saddlesupport in the mold a substantial distance away from the walls of themold, said saddle support having supporting means extending outwardlythrough the mold wall, molding a layer of resilient plastic material onthe inside of said mold while holding said saddle member in saidposition in the mold cavity, and bringing the saddle support intosupporting engagement with the wall of the toy after the toy istformed.

4. The method of forming an enclosed hollow rubber toy in'a mold ofwater-absorbing material having two side members and an intermediatelower member which comprisesproviding tubular means in the lowerintermediate member, locating a saddle support in the mold with asupporting element extending out through said tubular means, molding alayer of rubber particles from a rubber latex on the inside of said moldby compound rotation of the mold around different axes, holding thesaddle member away from the walls of the mold and out of contact withthe molded toy during the formation of the toy in the mold, removing thetwo side members of the mold, further drying the molded toy whilesupported 8 by the lower intermediate member, removing the toy from saidlower intermediate member after it is dried, sulr jecting the removedtoy to a curing operation, and bringing the saddle support intoengagement with the wall of the toy after the toy is cured.

References Cited in the file of this patent UNITED STATES PATENTS2,569,869 Rempel Oct. 2, 1951 2,730,765 Crafton et a1. Ian. 17, 19562,801,104 Yetter July 30, 1957 2,806,698 Thoeming Sept. 17., 19572,918,703 Beal Dec. 29, 1959 2,944,814 Thoeming July 12, 1960 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,031,720 Mayit 1962 Dietrich GO Rempel et ale It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 1, line 55 strike out "a"; column 2 line 18., after "rotary"insert casting column 6, line 60 for "toy" read article Signed andsealed this 28th day of August 1962,

(SEAL) Attest:

ESTON G. JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents

